eso8604-en-us — Science Release

Comet Halley Status; Observations at La Silla

18 February 1986

After the successful recovery of Comet Halley on 15 February, at the European Southern Observatory (ESO), observations have been made at the ESO La Silla Observatory every morning since. Accurate positions of the comet continue to be measured and transmitted within a few hours to the spacecraft centers in Darmstadt, Moscow, Tokyo and Pasadena. This is an important contribution to the accurate navigation of the five spacecrafts, including the European Space Agency's GIOTTO, now heading towards an encounter with Halley in early March.

In the morning of 18 February, it became apparent that an outburst from the comet nucleus must have taken place within the past 24 hours. On photographic plates from the ESO Double Astrograph, the nucleus was very bright and there were three jets emanating from it. Also bolometric measurements with the ESO 1 metre telescope showed that the comet was unusually bright in the infrared region of the spectrum.

Until now, the comet has only been visible low in the bright morning sky, just above the eastern horizon. It has therefore been difficult to observe the tail. Still, the presence of a one degree tail was seen on 17 February and today observations with the new ESO wide angle CCD Camera, which was specially designed to follow the development of Comet Halley, showed two tails pointed in the direction opposite to the sun.

A group of astronomers from the Ruhr University in Bochum, F.R. Germany, started observations of Halley in different colours with a multi-camera mounting.